The overall goal of this project is to determine whether frozen red cells stored at -25oC for periods up to six months will have an in vivo survival equal to that of frozen red cells stored at -65oC for periods up to 10 years and will meet the criteria established by the Food and Drug Administration Office of Biological Research and Review (FDA-OBRR) for the blood product Red Blood Cells Frozen. The specific aim of this project is to determine whether red cells frozen and stored at -25oC have sufficient recovery and in vitro biochemical characteristics to justify their use for transfusion therapy, i.e., at least 80% recovery of red cells following deglycerolization, normal 2,3, DPG levels and at least 6760% of the baseline ATP level. These studies are the first part of a development plan that would provide the technology to expand the capabilities of autologous blood donor programs to include the use of a simplified method for the freezing preservation at -25oC, and recovery of red blood cells that are suitable for transfusion. Such a program could potentially have wide use and accptance in community hosptials, blood banks, in underdeveloped areas where sophisticated freezing and storage equipment is not readily available and in the military establishment where every member of the armed forces is a potential blood donor.